This invention relates to a cooling apparatus for engines and, more particularly, to an engine cooling apparatus having an improved air-water separating function. Further, the invention relates to an engine cooling apparatus placed in juxtaposition with an intercooler provided in order to cool the intake air to the engine combustion chamber.
An arrangement well known in the art as an apparatus for cooling automobile engines generally is so adapted that the engine and radiator of the automobile are connected via a coolant passageway through which cooling water is circulated. When a large quantity of air mixes in with the cooling water as the engine runs, oxidation of a coolant such as a rust-preventing agent mixed together with the cooling water in advance, overheating and cavitation occur much sooner. This makes it necessary to separate the air that mixes in with the coolant and discharge the air to the outside of the cooling flow path.
As an expedient for providing a function for separating air from cooling water (which function shall be referred to as an "air-water separating function" hereinafter), it is well known to furnish a pressure valve provided on a radiator cap at the top of the radiator, which radiator is installed so as to be substantially perpendicular to the ground. In this well-known example, the air mixing in with the cooling water is separated via the pressure valve, after which the air is collected in a reservoir tank.
In vehicles in which the radiator is tilted forward in order to reduce the area of the forward projection of the vehicle body, the pressure valve cannot be provided on the radiator cap located on the top of the radiator in the manner mentioned above. Accordingly, an air-water separating tank having a pressure valve is installed at a point along the passageway of the cooling water, and the tank serves to separate the air from the water. For example, the specification of Japanese Utility Model Application Laid-Open (KOKAI) No. 55-146824 discloses a technique in which the cooling water of the engine is cooled by a radiator and air is removed from the cooling water by the air-water separating tank, whereby cooling efficiency of the engine is improved.
In the above-described arrangement wherein the pressure valve is provided on the top of the radiator, some of the cooling water flows out into the reservoir tank along with the air via the pressure valve and is discharged to the outside.
In the other arrangement wherein the air-water separating tank is provided in series with the passageway of the cooling water, the amount of cooling water which flows into the air-water separating tank is approximately the same as that which flows into the radiator, and therefore the air-water separating tank is designed to have a large capacity.
In the latest high-performance automobiles, the intake air of the engine is compressed by a turbo-supercharger and the compressed intake air is passed through an intercooler so as to be cooled, thereby increasing the amount of intake air fed into the combustion chamber. To accomplish this, the intercooler is so adapted that an upper tank into which the intake air flows and a lower tank which feeds the intake air into the engine are connected by a number of pipes, the outer peripheral surface of each of which is provided with innumerable fixed cooling fins so that the intake air passing through the pipes will be cooled by the wind produced as the vehicle travels.
In the intercooler thus constructed, the wind introduced to the interior of the engine room from an opening in the front of the vehicle body is made to blow against the intercooler in a positive fashion in order to enhance the effect of cooling upon the intake air passing through the pipes.
In the arrangement in which the air-water separating tank is provided in series with the passageway of the cooling water, a problem is encountered wherein the air-water separating tank must have a large capacity, as mentioned earlier. If it is attempted to reduce the capacity in order to make the air-water separating tank more compact, the air-water separating function is rendered inadequate and some of the cooling water flows into the reservoir tank along with the air. This leads to insufficiency in terms of the circulating cooling water and to risk of overheating. Furthermore, since the intercooler is constructed as set forth above, it does not possess sufficient rigidity to the strong wind caused by the traveling vehicle. When the air impacts strongly against the intercooler, the intercooler core provided with the cooling fins vibrates and produces noise, and there is the danger that the intercooler will be damaged.